In oilfield applications, pump assemblies are commonly invoked for pumping fluid at high pressures from the surface of the well downhole to a wellbore. Such oilfield operations frequently involve hydraulic fracturing. For hydraulic fracturing (herein abbreviated “fracking” for convenience), an abrasive-containing fluid such as sand and other fracking or frac materials (collectively termed “proppant”) are pumped through the wellbore and into targeted regions thereof, to create side “fractures” within the underlying hydrocarbon formations.
As is will known in the art, in order to create such fractures, frac fluid containing abrasive proppant is pumped downhole at extremely high pressures not only to facilitate fracture-creation, but also to sustain the propped-open structures. As will be appreciated by those skilled in the art, these propped-open structures afford additional pathways for underground oil and gas deposits to flow from underground formations to the well surface, thereby enhancing well production.
Prior art apparatus and methodology for transporting frac fluid containing sand and proppant suffer from several long-standing disadvantages. For instance, after being loaded onto special-purpose pneumatic trucks or railcars, frac sand and proppant have typically not been well sealed from environmental incursions during transfer. As a consequence of such environmental incursions, the integrity of this material has been seriously undermined whereupon significant degradation attributable to cumulative effects of abrasion and friction, and exposure to moisture and rain occur during material transfer operations. Since it has been difficult—if not virtually impossible—for special-purpose railcars and pneumatic trucks to be brought sufficiently close to well sites, it has become a prevalent occurrence for several material transfers to be prerequisite for ultimate delivery of sufficient frac sand and/or proppant to the intended well site so that fracking operations may be initiated. Moreover, pneumatic trucks are frequently unavailable and unloading of frac sand from trucks or railcars is likewise frequently delayed, wherein railcars remain idle, with railroads charging significant demurrage fees.
Accordingly, what is needed in the art is an apparatus and concomitant methodology for improving the logistics for transporting frac sand and proppants proximal to well sites to avoid these several longstanding limitations and disadvantages prevalent in the prior art. This need is fulfilled by embodiments of the present invention which contemplate novel application of standard ISO shipping containers to accommodate an internal structure adapted to support and strengthen the walls and floor of such ISO shipping containers and a valve apparatus configured to efficiently and securely achieve prerequisite sand and proppant material transfer from such adapted containers to fracking operations regardless of the remoteness and limited accessibility of a diversity of well site locations.
Such intermodal shipping or freight containers enable reusable transport and storage units for moving products and raw materials between locations. Containers manufactured to ISO specifications are commonly be referred to as “ISO containers,” wherein, as well known in the shipping art, ISO corresponds to an acronym for the International Organization for Standardization which promulgates worldwide industrial and commercial standards. ISO containers suitable for sand and proppant transfer and delivery to well site locations should preferably be sized with 20-foot length, and with 8½-foot height and 8-foot width. To be able to accommodate the substantial quantity of materials stored and transported to well site locations, often over rough terrain and under exigent conditions, the container's external frame should preferably be reinforced with appropriate bracing and trusses.
FIGS. 11 and 12 depict typical standard ISO shipping containers suitable for receiving embodiments of the present invention. More particularly, FIG. 11 depicts an end perspective view of a standard ISO container, with its end-opening doors disposed in an open position. FIG. 12 depicts a frontal perspective view of a portion of internal bracing framework incorporated into the ISO container depicted in FIG. 11, wherein the storage capacity of the enclosing walls and the like are reinforced with braces and trusses as taught hereunder to accommodate the quantity of sand and proppant as will be described hereinafter. As clearly shown in FIG. 12, the standard ISO container should preferably have a clear span—a span devoid of columns or structural walls or the like present. Of course, any of a plethora of known bracing and truss designs may be implemented in order to achieve the prerequisite container strength and capacity contemplated herein throughout the container's 20-foot length.
Once a standard 20-foot ISO container has been suitably reinforced with an internal bracing structure, an apparatus is needed for timely transferring the enclosed sand or proppant to the high pressure delivery system at the well site, preferably nominally within an hour's time frame. This material transfer apparatus comprises a hopper/valve assembly configured to deliver the material to ports at the well site where in situ fracturing operations will be conducted.